While I wouldn't suggest that Chua's very controlling parenting philosophies be universally adopted, I think she makes some good points that are worth thinking about. For instance, since it takes hard work to get good at anything, and since being good at something makes it more fun, Chua believes pushing your child to work hard is a way of making them ultimately happier. Also, Chua points out that her view of her daughters is complimentary. She drives them so hard because she sees them as strong. She feels that always letting a child give up is bad for their self-esteem and doesn't prepare them for the future.
That said, by the end of the book even Chua admits her approach doesn't always work. Her younger daughter Lulu pushed back with great defiance against Chua's controlling manner, but even Lulu admits she's glad her mother forced her to work hard when she was younger. It's not hard to see that Lulu's success at tennis and "improv" comedy, pastimes her mother did not sanction, is at least partly due to the determination and drive her mother helped instill in her.
Lulu's older sister Sophia